[Clinical analysis of long-term survival and influencing factors of chimeric antigen receptor T-cell therapy in relapsed/refractory acute B-cell lymphoblastic leukemia].

Objective: To analyze the survival and influencing factors of chimeric antigen receptor (CAR) T-cell therapy in relapsed/refractory acute B-cell lymphoblastic leukemia (R/R B-ALL) . Methods: Clinical information of patients who received CAR-T-cell therapy and achieved complete remission of R/R B-ALL between May 2015 and June 2018 at the Shaanxi Provincial People's Hospital was obtained. Kaplan-Meier analysis was used to evaluate the overall survival (OS) and leukemia-free survival (LFS) times of patients, and Cox regression analysis was performed to analyze the prognostic factors that affect patient survival after CAR-T therapy. Results: Among the 38 patients with R/R B-ALL, 21 were men, with a median age of 25 (6-59) years and a median OS time of 18 (95% CI 3-33) months. Multivariate Cox regression analysis showed that positive MLL-AF4 fusion gene expression was an independent risk factor for OS and LFS (OS: HR=4.888, 95% CI 1.375-17.374, P=0.014; LFS: HR=6.683, 95% CI 1.815-24.608, P=0.004). Maintenance therapy was a protective factor for OS and LFS (OS: HR=0.153, 95% CI 0.054-0.432, P<0.001; LFS: HR=0.138, 95% CI 0.050-0.382, P<0.001). In patients with MRD negative conversion, LFS benefit (HR=0.209, 95% CI 0.055-0.797, P=0.022) and OS difference was statistically insignificant (P=0.111). Moreover, patients with high tumor burden were risk factors for OS and LFS at the level of 0.1 (OS: HR=2.662, 95% CI 0.987-7.184, P=0.053; LFS: HR=2.452, 95% CI 0.949-6.339, P=0.064) . Conclusion: High tumor burden and high-risk genetics may affect the long-term survival rate of patients with R/R B-ALL receiving CAR-T, and lenalidomide-based maintenance therapy may improve their prognosis.